The present invention relates to a process for mass-production of dihomo-.gamma.-linolenic acid (.DELTA.8, 11, 14-eicosatrieneic acid) at low production costs by a fermentation method, and an inhibitor for an unsaturation reaction at a .DELTA.5-position of fatty acid by microorganisms and animal cells.
For production of dihomo-.gamma.-linolenic acid, there is known a method in which lipid containing dihomo-.gamma.-linolenic is produced by adding sesame oil to a culture medium containing glucose as a main component and cultivating a microorganism belonging to the genus Mortierella (H. Yamada et al., J. Am. Oil Chem, Soc., Vol. 66, p. 237-241 (1989)).
As an inhibitor for an unsaturation reaction at a .DELTA.5-position of fatty acid, sesamin or episesamin contained in sesame oil is known (H. Yamada et al., Nippon Nogei Kagakukaishi, Vol. 63, p. 676 (1989)). However, sesamin and episesamin are unsuitable for practical use, because their mass-production costs are high.